With increasing progress of technology and science, many electrical devices are developed toward miniaturization, high performance and high heat-dissipating efficiency. As known, it is difficult to produce an electrical device having all of the benefits of miniaturization, high performance and high heat-dissipating efficiency.
Take an induction cooker for example. The induction cooker usually has an induction coil. When a current flows through an induction coil of the induction cooker, electromagnetic induction is performed to produce eddy current, thereby heating a foodstuff container. FIG. 1 is a schematic view illustrating a conventional induction coil. As shown in FIG. 1, the induction coil 10 has a multi-turn planar spiral coil structure by winding a conductive wire 11 for many turns of loops on the same plane. Since all loops 101 of the induction coil 10 are closely arranged, the diameter D1 of the induction coil 10 is smaller than the foodstuff container (not shown) without impairing the performance of the electrical device. However, since the closely arranged loops 101 may hinder passage of airflow, the efficacy of the forced convection within the electrical device is impaired and a large back pressure is generated. Moreover, when electric current passes through the induction coil 10, every two adjacent loops 101 may interfere with each other. In this situation, the magnitude of eddy current between the two adjacent loops 101 is increased, the conduction loss is increased, and the performance of the electrical device is deteriorated.
For solving the above drawbacks, another induction coil is disclosed. FIG. 2 is a schematic view illustrating another conventional induction coil. In the induction coil 20 of FIG. 2, there is a vacant portion G between every two adjacent loops 201. Although the use of the induction coil 20 may increase the heat-dissipating efficiency, there are still some drawbacks. For example, since the diameter D2 of the induction coil 20 is too large, the overall volume of the electrical device is increased. In addition, if the foodstuff container fails to fully shelter the induction coil 20, the operating efficiency of the electrical device is unsatisfied.
Therefore, there is a need of providing a coil assembly, a fabricating method for the coil assembly and an electrical device having the coil assembly so as to obviate the drawbacks encountered from the prior art.